The goal of our research is to elucidate the pathways by which malarial parasites obtain free amino acids from degradation of the host cell's protein, especially hemoglobin. Our proposed studies fall into two major areas: 1. Isolation and Characterization of Parasite Proteases which Participate in the Degradation of Hemoglobin within the Parasite's Food Vacuole. Both acid and non-acid proteases from P. falciparum will be characterized, using a variety of kinetic/inhibition approaches. The extent to which these proteases, singly and collectively, degrade hemoglobin into free amino acids will be determined. 2. Evaluation of the Role of Ubiquitin-requiring, Nonlysosomal Protein Turnover in P. falciparum. P. falciparum will be examined for the presence of an ATP-dependent, ubiquitin-requiring pathway for protein degradation. The role of this pathway in the degradation of hemoglobin will be determined.